Abstract A two year field experiment was carried out to evaluate the effects of three row and eight row seeding on the total phenolic compound TPC, total flavonoid content TFC, hydrolyzed HTC and condensed tannin CTC, antioxidant activity ABTS assay, protein content and soluble dietary fiber SDF and insoluble dietary fiber IDF in the extracts of lentil Lens culinaris L. and grass pea Lathyrus communis L. cultivated under organic farming. The aim of this study was to determine whether row spacing used for seeding in organic farming systems for lentil and grass pea is a suitable method to increase the accumulation of antioxidant compounds in these crops. Grass pea showed the highest mean SDF and protein while lentil varieties showed the greatest and significant content of all of the antioxidant compounds. In lentil, there were increases in TPC 52%, HTC 73%, TFC 85% and CTC 41%, passing from three rows to eight rows, while in grass pea, the increases were lower, and only significant for TFC and CTC 37%, 13% respectively. In both lentils and grass pea, the highest correlation coefficient was between TPC and HTC, which indicates that the HTC includes the predominant phenolic compounds in lentil as well as in grass pea r = 0.98, 0.71 p < 0.001, respectively. Regardless of legume species, TPC, HTC, TFC and CTC showed significant p < 0.001 and linear correlations with the ABTS assay. These data confirm the key role of row spacing for the improvement of the antioxidant properties of lentil in organic farming; moreover, they hint at the major responsiveness and adaptation of lentil to environmental stimulus with respect to grass pea. View Full-Text